Distinct regions of the colicin A translocation domain are involved in the interaction with TolA and TolB proteins upon import into Escherichia coli.
Group A colicins need proteins of the Escherichia coli envelope Tol complex (TolA, TolB, TolQ and TolR) to reach their cellular target. The N-terminal domain of colicins is involved in the import process. The N-terminal domains of colicins A and E1 have been shown to interact with TolA, and the N-terminal domain of colicin E3 has been shown to interact with TolB. We found that a pentapeptide conserved in the N-terminal domain of all group A colicins, the 'TolA box', was important for colicin A import but was not involved in the colicin A-TolA interaction. It was, however, involved in the colicin A-TolB interaction. The interactions of colicin A N-terminal domain deletion mutants with TolA and TolB were investigated. Random mutagenesis was performed on a construct allowing the colicin A N-terminal domain to be exported in the bacteria periplasm. This enabled us to select mutant protein domains unable to compete with the wild-type domain of the entire colicin A for import into the cells. Our results demonstrate that different regions of the colicin A N-terminal domain interact with TolA and TolB. The colicin A N-terminal domain was also shown to form a trimeric complex with TolA and TolB.
Bouveret
E
E
Laboratoire d'Ingénierie des Systèmes Macromoléculaires, Institut de Biologie Structurale et Microbiologie, CNRS, Marseille, France.
Rigal
A
A
Lazdunski
C
C
Bénédetti
H
H
D001426:Bacterial Proteins / Q000378:metabolism*; D015153:Blotting, Western; D003087:Colicins / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins; D008565:Membrane Proteins / Q000378:metabolism; D016296:Mutagenesis; D033903:Periplasmic Proteins; D010641:Phenotype; D010957:Plasmids / Q000737:chemistry; D016133:Polymerase Chain Reaction
D001426:Bacterial Proteins; D003087:Colicins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D033903:Periplasmic Proteins; C062093:tolA protein, E coli; C062094:tolB protein, E coli